Bending tool for bending deformable workpieces, such as metal sheets and the like

ABSTRACT

A device for bending deformable workpieces, especially metal sheets, in which in the path of movement of the male die below a holding jaw on opposite sides of said die there is provided an elastic counter bearing each respectively located in recess means adjacent the mold bottom through which extend a reciprocable piston operable both as counterpressure plate during the shaping action of said die and as an ejector at the end of said shaping action, said elastic bearing means extending into the path of movement of said die prior to its shaping operation and being elastically displaceable by said die during its shaping operation into said recess means adjacent the mold bottom.

United States Patent Koschatzky [s41 BENDING TOOL FOR BENDING DEFORMABLE WORKPIECES, SUCH 7 AS METAL SHEETS AND THE LIKE [72] Inventor: Karl Koschatzky, Numberg, Germany [73] Assignee: Maschinentabrlk Augsburg-Numberg Aktiengesellschaft Zweignlederlassung Nurnberg, Numberg, Germany [22] Filed: 'Jan. 27, 1971 211 App]. No.: 110,099

[30] Foreign Application Priority Data 4/1925 Gansert et a1. ..72/ S7 [451 Dec. 12,1972

3,568,487 3/1971 Riesener ..72/60 FOREIGN PATENTS OR APPLICATIONS 951,807 11/1956 Germany ..72/57 795,359 1/1936 France ..72/57 Primary Examiner-Richard J. Herbst Attorney-Walter Becker [57] ABSTRACT A device for bending deformable workpieces, especially metal sheets, in which in the path of movement of the male die below a holding jaw on opposite sides of said die there is provided an elastic counter bearing each respectively located in recess means adjacent the mold bottom through which extend a reciprocable piston operable both as counterpressure plate during the shaping action of said die and as an ejector at the end of said shaping action, said elastic bearing means extending into the path of movement of said die prior to its shaping operation and being elastically displaceable by said die during its shaping operation into said recess means adjacent the mold bottom.

5 Claims, 2 Drawing Figures BENDING TOOL FOR BENDING DEFORMABLE WORKPIECES, SUCH AS METAL SHEETS AND THE LIKE The present invention relates to a tool for bending deformable workpieces such as metal sheets arrd the like, especially for making burner element boxes for core reactors. More specifically, the present invention relates to a bending tool of the above type in connection with a profile mold arranged on a machine table and with a die for pressing the workpiece into said mold, while the profile mold corresponds to the dimensions of the profile to be produced and at its folding edges has fixed jaws while the bottom of said mold has at least one opening for an ejecting tool.

, It is known by means of folding presses,'bending machines, or the like, to produce various profiles and to make these profiles of metal sheet, synthetic material, or other deformable workpieces. When employing presses, frequently for the production of the desired profile, a profile mold is employed and a die, by means of which, the workpiece is pressed into the profile mold. In order to be able after effected pressing to remove the workpiece from the profile mold, profile molds are equipped with ejectors which, depending on the design and the size of the workpiece to be ejected, may be actuated pneumatically, hydraulically, or mechanically. Profile molds employed for the production of desired profiles have the shape of the profile to be produced while, as a rule, they have a depression into which the workpiece is pressed by means of a die until the desired profile shape has been obtained. When pressing the workpiece into the profile mold, the workpiece is drawn around the die while the edges are formed by jaws provided on the profile mold and by the corners of the die. While with machines of this type various profile shapes can be obtained, difficulties are encountered when, for instance, profiles are to be produced which require a high precision as to their dimensions. Such profiles are employed, for instance, for making element boxes for the burner rods of core reactors and, more specifically, for the manufacture of such boxes which are composed of individual profile pieces and are connected by welding. These element boxes, which may have a square, rectangular, or polygonal cross-sectional shape require for their manufacture such tools which on one hand will assure high measurement precision, and on the other hand will permit the manufacture of element parts, i.e., of the individual profiles without damaging the workpiece. It is at this point where the present invention starts. More specifically, it is an object of the present invention to provide a tool for bending deformable workpieces such as metal sheets, by means of which a high precision as to the desired profile will be assured while damage to the workpieces will, for all practical reasons, be eliminated.

This object and other objects and advantages of the invention will appear more clearly from the following specification, in connection with the accompanying drawings, in which:

FIG. 1 illustrates a cross section through a bending press with a workpiece prior to the shaping of the latter.

FIG. 2 is a cross section through a bending press according to FIG. 1 showing the workpiece in its deformed or shaped condition.

The present invention is characterized primarily in that when viewing in the direction of movement of the die, below each jaw there is provided a recess or chamber having arranged therein an elastic counter bearing, and is furthermore characterized in that the die has mantle surfaces which from its bending plane extend inwardly, and in the bending plane itself has a mantle surface corresponding to the shape to be produced. Against said last mentioned mantle surface, a piston acting as ejector and counterpressure plate is adapted to be pressed during the pressing operation of the workpiece interposed therebetween.

Referring now to the drawings in detail, the tool according to the invention primarily comprises a profile mold l which is mounted on a machine table 2 and furthermore comprises a piston 5 which is arranged in an opening 3 provided in the bottom 4 of the profile mold, said piston 5 being movable in said opening 3. The tool according to the invention furthermore comprises a die 6 adapted to be pressed into the profile mold. With this tool, profile mold 1 forms the stationary tool part whereas the die 6 forms the movable tool part. Die 6 is arranged on a cross beam 7 by means of which said die can be moved by a pressing device 8. The profile mold l which corresponds to the cross-sectional shape of the profile to be produced and which in the particular example shown is employed for producing U-shaped profiles has a cavity 9 which is confined at the lower end by the bottom 4 and the piston 5 and is laterally confined by the recesses 10. The recesses 10 of the member 9 are formed by confining walls 11 and and by jaws 12 mounted thereon. The jaws 12 form the upper plane of the profile mold l and are exchangeably connected to the confining walls 11 by means of screws indicated by center lines 12a. Below the jaws 12 there is in each recess 10 provided an elastic counter bearing 13 which may be designed as a rubber ball or rubber roller, depending on the profile to be produced. During the bending of U-shaped rails as they are employed, for instance, for the manufacture of burner element boxes, the member 9 extends over the entire length of the profile body to be produced while also the elastic counter bearings 13 in the form of rubber rollers likewise extend over the entire length of the member 9, or the recesses 10 therefor. As will be seen from the cross section of the produced tool, the elastic counter bearings 13 have a circular cross section and have one portion of the cross section thereof, extend into the free space of the member 9. These elastic counter bearings 13 which when not under load do not completely fill the space of the recesses 10 are, during the pressing of the workpiece 14 into the profile mold l, displaced outwardly, i.e. into the recesses. The workpiece 14 which is to be deformed by means of the die 6 is likewise placed upon the jaws l2, and subsequently thereto the die 6 above the workpiece is moved against the latter. In order to assure a smooth and precise deformation of the workpiece l4, simultaneously also the piston 5 is moved against the workpiece so that piston 5 occupies the dot-dash line position 5'. Piston 5, in addition to acting as an ejector, also serves as counterpressure plate. Piston 5 and die 6 are pressed against the workpiece 14 to such an extent that the pressure of the die exceeds the pressure exerted by the piston. In view of the fact that the pressure of the die 6 predominates, the workpiece 16 is gradually lowered into the profile mold while piston 5 gradually recedes until after displacement of the elastic counter bearing 13 the workpiece 14 has reached the bottom 4 of the profile mold 1. In view of the employment of the elastic counter bearings 13, the upwardly extending legs l5, 16 (FIG. 2) of the U-shaped profile are pressed against the inwardly slanted mantle surfaces 17 of the die 6. These inwardly pressed legs 15, 16 of the workpiece 14 may with simple workpieces during the movement of die 6 out of the workpieces be again directed outwardly while the tension inherent to said legs 15, 16 will be reduced. With workpieces 14, however, which have to meet a high precision as to dimensions, it is suggested to withdraw the workpieces according to their length from die 6 and to bend toward the outside, i.e., to put straight, the inwardly bent legs l5, 16 after the workpiece has been withdrawn from the die. The ejection of the pressed workpiece 14 may, when simple workpieces are involved, be effected by means of the piston 5 which now is anew moved upwardly by a hydraulic, pneumatic, or mechanical device 18.

The workpiece 14 produced in this manner is precision dimensioned without having been subjected to damage. In order to be able to treat the workpiece 14 in a careful manner, the bending edges 19 of the die 6 are, within the region of the bending plane, provided with corresponding rounded portions, and the bending edges 20 of the jaws 12 are likewise within the region of the bending plane provided with rounded portions. The degree of the rounding depends on the degree of the desired cross-sectional shape, and as a rule is relatively small when the manufacture of boxes with comers is involved.

For purposes of producing long profiles as, for instance, element boxes, with a length of, for instance, from 4 to 5 meters, it is advisable to produce at least the die 6 from individual parts, for instance, meter pieces which after being assembled are together post machined for purposes of obtaining a precise machining. The piston 5 serving as ejector of the workpieces l4 and for pressing against the workpieces 14 may likewise, for purposes of a more precise machining, correspond to the length of the die 6. This has the advantage that when counter pressing the workpiece 14, the latter is counter pressed over its entire length so that bulges, or the like, cannot form.

The workpiece according to the invention serves for producing pressed profiles of approximately any desired shape without being limited to the manufacture of element boxes or the profiled parts thereof. The work too] according to the invention has been discussed merely by way of example as a press for U- profiles. It is a matter of course that by means of this tool also other profile types can be produced as, for instance, those having a polygonal or arc-sectional cross section. The tool according to the invention may be mounted on any desired bending machines, and also those now in use.

As will be seen from the above, by means of the present invention, it is possible to produce pressed profiles with high precision as to dimensions and also without damaging the walls, in a simple and relatively inexpensive manner. By employing the elastic counter bearings 13, the workpiece, in most instances metal sheet, is bent about the shape of the die in a careful and precise manner. When producing element boxes for burner rods which are composed of two or more profile parts, the present invention, due to the design of the die, brings about the advantage that the legs which during the pressing operation are bent inwardly may, prior to welding the parts together, be bent outwardly in order in this way to reduce tensions in the material. This is of a foremost importance with burner element boxes, inasmuch as restrictions in the free width of the element boxes cannot be tolerated for reasons of a bending free guidance of the burner rods.

A further advantage of the invention consists in the employment of elastic counter bearings because by means of said counter bearings 13 an exact bending of the workpieces around the bending edges of the die is possible. In addition thereto, the invention has the advantage that by means of the tool according to the invention, it is possible to produce also extremely long profile parts in an easy and inexpensive manner. This is of particular importance in connection with the production of profiles, which as a rule, are mass produced.

It is, of course, to be understood that the present invention is, by no means, limited to the particular showing in the drawings, but also comprises any modifications within the scope of the appended claims.

What I claim is:

1. A device for bending deformable workpieces into accurate U-form out of flat plates, especially metal sheets, which includes in combination: supporting means, mold means supported by said supporting means and having a cavity adapted to receive the workpiece while it is being deformed, a portion of said cavity being defined by a mold bottom having an opening therethrough, elastic counter bearing means supported by said bottom and arranged around that end of said bore which is adjacent said bottom, said elastic counter bearing means during bending procedure being effective upon the workpiece only in the range of workpiece bending edges, jaw means detachably connected to said mold for holding said elastic counter bearing means connected to said mold, piston means reciprocable in said bore and operable to act both as counterpressure member and as ejector, male die means arranged substantially coaxially with regard to said piston means and operable to enter said mold and to move between said elastic counter bearing means to thereby deform a workpiece placed between said die means and said mold, at least those lateral edges of said die means being rounded which during the deforming operation engage said elastic counter bearing means, said die means having inwardly bent side surfaces at an incline to compensate return springiness and opening during subsequent annealing procedure and having a level bottom surface, and power means respectively operatively connected to said piston means and said die means for actuating the same being pressed against the workpiece to such an extent that pressure of said die means exceeds the pressure exerted by said piston means over the entire length thereby to assure a completely even bottom surface, said opening and said piston means extending over the length of the workpiece to be formed.

2. A device in combination according to claim 1, in which said die means has a trapezoidal cross section with the smaller side of the trapezoid facing away from said mold bottom.

4. A device in combination according to claim 3, in

which the length of said recess means corresponds to the length of the workpiece to be deformed.

5. A device in combination according to claim 4, in which said elastic counter bearing means extend over the length of said recess means in the form of rubber balls. 

1. A device for bending deformable workpieces into accurate Uform out of flat plates, especially metal sheets, which includes in combination: supporting means, mold means supported by said supporting means and having a cavity adapted to receive the workpiece while it is being deformed, a portion of said cavity being defined by a mold bottom having an opening therethrough, elastic counter bearing means supported by said bottom and arranged around that end of said bore which is adjacent said bottom, said elastic counter bearing means during bending procedure being effective upon the workpiece only in the range of workpiece bending edges, jaw means detachably connected to said mold for holding said elastic counter bearing means connected to said mold, piston means reciprocable in said bore and operable to act both as counterpressure member and as ejector, male die means arranged substantially coaxially with regard to said piston means and operable to enter said mold and to move between said elastic counter bearing means to thereby deform a workpiece placed between said die means and said mold, at least those lateral edges of said die means being rounded which during the deforming operation engage said elastic counter bearing means, said die means having inwardly bent side surfaces at an incline to compensate return springiness and opening during subsequent annealing procedure and having a level bottom surface, and power means respectively operatively connected to said piston means and said die means for actuating the same being pressed against the workpiece to such an extent that pressure of said die means exceeds the pressure exerted by said piston means over the entire length thereby to assure a completely even bottom surface, said opening and said piston means extending over the length of the workpiece to be formed.
 2. A device in combination according to claim 1, in which said die means has a trapezoidal cross section with the smaller side of the trapezoid facing away from said mold bottom.
 3. A device in combination according to claim 2, in which the cavity of said mold adjacent said bottom includes recess means containing said elastic counter bearing means, said counter bearing means normally extending partially into the forming path of said die means and only partially into said recess means and being elastically deformable and displaceable by said die means out of the path of movement of the latter and further into said recess means.
 4. A device in combination according to claim 3, in which the length of said recess means corresponds to the length of the workpiece to be deformed.
 5. A device in combination according to claim 4, in which said elastic counter bearing means extend over the length of said recess means in the form of rubber balls. 